is a site about T1 service
in that site it explains how t1 works and
T-1 stands for Trunk Level One, it is a digital transmission link with a total speed of 1.544 Mbps. A T-1 Internet connection is comprised of two parts, the local loop charge, the phone circuit that connects your location to the Internet point of presence (POP) and the actual Internet bandwidth access port charge.
DS-O (Digital Signal Level 0) - A non-switched dedicated, fractional or burstable service that can be provisioned as a private line point-to-point and multi-point service. Designed for full duplex transmission of voice, analog data and digital signals transmitting at speeds of 56 KBPS. The circuit is BI-directional and can move information in both directions.
but however Look at the site for more info.
also regular phone lines are slow. most companies have VOIP (Voice OverIP)
I think the best is Optical or wifi extension or Microwave, but however Microwave towers are quite expensive to buld and requre additional approvals by athorities such as FCC and local regulatory committies due to potential interferrence and Local building codes. If you are wating to use this I suggest you contact those.
also New wireless standard known as WiMAX is coming out it will High speed up to 70Mbps connectivity and coverage for at least 5-10 miles.
This is supposed to replace WiFi and is still developing.